LONDON (REUTERS) - Two British Muslim converts were found guilty of murder on Thursday for hacking a soldier to death in broad daylight on a London street in a gruesome killing that horrified the nation.

The murder, its impact magnified by video footage showing the culprits with blood-soaked hands explaining their actions, provoked a rise in hate crimes against Muslims in Britain, anti-Islamist street protests and government promises of tougher action on radical Islamist preachers.

British spy chiefs are facing questions over whether they could have prevented the attack on Drummer Lee Rigby, charges that echo previous criticisms of the security services.

A jury at London's Old Bailey criminal court took about 90 minutes to unanimously find Michael Adebolajo, 29, and Michael Adebowale, 22, guilty of murdering Rigby, 25, an Afghan war veteran, near an army barracks in Woolwich on May 22.

The court heard they had driven around the area looking for a soldier and ran over Rigby, who was carrying a military backpack, then attacked his unconscious body with knives and a meat cleaver, trying to behead him.

They then dragged his corpse into the middle of the road where Adebolajo asked a bystander to video them, brandishing their weapons with their hands covered blood, as he calmly explained what he had done to the shock of startled passers-by.

"We swear by almighty Allah we will never stop fighting you.

The only reason we've killed this man today is because Muslims are dying daily by British soldiers," Adebolajo said minutes after murdering Rigby, who had a two-year-old son.

"He is an eye for an eye, a tooth for a tooth."

Further footage captured the two men trying to ambush armed police as they arrived on the scene. Adebolajo charged towards a police car wielding a cleaver while Adebowale waited, clutching a rusty, unloaded revolver, hoping to be shot dead and martyred but officers fired and only wounded them.

The two men were found not guilty of the attempted murder of a police officer on Thursday.

During the trial, the pair never denied killing Rigby but Adebolajo argued the act should not be considered murder but an act of war - a war for Allah in response to Britain's foreign policy and Western wars in nations such as Iraq and Afghanistan.

"I am a soldier of Allah. This is war," Adebolajo told the court during calm, composed testimony watched by tearful members of Rigby's family including his partner and mother.

The Crown Prosecution Service said it would ask the court to find that the murder was motivated by terrorism when the defendants come to be sentenced in January.

After the men were convicted of murder, Rigby's family told reporters outside the court that justice had been served.

"Unfortunately no amount of justice can bring Lee back.

These people have taken him away from us forever," they said in a statement.

It was the first killing by Islamist militants in London since four suicide bombers killed 52 people in al Qaeda-inspired attacks on the capital's transport network in July 2005.

Home Secretary Theresa May said Rigby's murder had "united the entire nation in condemnation" as a list of politicians, campaigners and faith groups paid tribute to the murdered soldier and denounced the actions of the killers.

Mr Farooq Murad, secretary general of the Muslim Council of Britain, described the murder as a "barbaric act" that disgusted the vast majority of Britain's 2.7 million Muslims.

"They claimed that their act was done for those suffering in wars in Muslim lands. But it is my contention that the vast majority of our affected brothers and sisters would have nothing to do with this phoney act done in their name," he said.

"We must all work hard to heal the divisions caused by this act." Britain's MI5 domestic intelligence agency is facing an investigation into whether it could have done more to stop the Woolwich attack, with a parliamentary committee examining what security services knew about the two men.

Both are Muslim converts from Christian Nigerian families and they previously handed out radical Islamist pamphlets and attended protests by the banned organisation Al Muhajiroun, many of whose members have been convicted of terrorism offences.

They were known to MI5, but not considered serious threats.

Adebolajo, who also goes by the name Mujahid Abu Hamza, is believed to have come to the notice of MI5 in 2011 when he was suspected of trying to join the Somalian Islamist group al Shabaab but was arrested by Kenyan police.

Friends and colleagues of Adebolajo have alleged he was tortured and sexually abused in custody after being arrested in Kenya en route to Somalia, and then later harassed by MI5 agents, suggesting this might have pushed him over the edge.

Assistant Commission Cressida Dick of the Metropolitan Police, Britain's most senior counter-terrorism officer, said Rigby's murderers appeared "lone wolves", acting without instruction either at home or from abroad.